1. Technical Field
The present invention relates to a liquid ejection apparatus which ejects liquid onto a recording medium, in particular, relates to a liquid ejection apparatus including a waste liquid unit for reserving waste liquid which has been wastefully ejected from a liquid ejection head.
2. Related Art
There is a recording apparatus as an example of a liquid ejection apparatus and there is an ink jet printer as an example of the recording apparatus. In the ink jet printer, ink discharged from an ink jet recording head does not always land onto a recording paper as an example of a recording medium in some case. In other words, ink is wastefully ejected at a predetermined portion intentionally in some case.
For example, in an ink jet printer which can execute so-called borderless recording in which recording is performed on the entire recording paper without margins, a groove is formed on an upper surface of a supporting member (platen) arranged so as to be opposed to an ink jet recording head. Further, in such ink jet printer, ink discharged onto a region deviated from edges of the recording paper is wastefully ejected into the groove. An ink discharge hole is provided on a bottom of the groove and ink which has been wastefully ejected into the groove is discharged to the lower side through the ink discharge hole so as to be introduced to a waste liquid unit which reserves waste liquid.
Whether or not an ink jet printer executes the borderless recording, a maintenance unit which performs maintenance on an ink jet recording head is provided in the ink jet printer. The maintenance unit includes a capping unit which caps the ink jet recording head and a pump unit which generates a negative pressure in a cap. The maintenance unit sucks ink through an ink discharge hole on the ink jet recording head and discharges the sucked ink to a waste liquid unit.
If waste ink is repeatedly discharged as described above, the waste liquid unit is filled with waste liquid. When the waste liquid unit is filled with waste liquid, subsequent recording operations cannot be executed. In particular, since an ink jet printer for business use is required to have longer lifetime, it is important to manage a waste ink reservation amount in the waste liquid unit.
Then, an ink jet recording apparatus in which the waste liquid unit is provided on a printer main body in a detachable manner, and a user can exchange the waste liquid unit when the waste liquid unit is filled with waste liquid has been already proposed (JP-A-6-234209).
As for lifetimes of parts used in an ink jet printer, an exchange frequency of the waste liquid unit is extremely less in comparison with an exchange frequency of an ink cartridge, for example, in general. On the other hand, since the waste liquid unit reserves waste liquid, there are risks that user's hands may possibly become dirty at the time of exchange and an inner portion of the apparatus is caused to be contaminated. In addition, if the waste liquid unit is detached carelessly while a maintenance operation is being executed on the ink jet recording head, there arises a risk that waste liquid flows out into the apparatus from an ink tube that is introducing the waste liquid to the waste liquid unit.
In addition, when a user performs an operation of exchanging the waste liquid unit, a controller of the ink jet printer needs to grasp a waste liquid reservation amount in the waste liquid unit. Then, when the waste liquid unit is filled with waste liquid, the controller is required to notify the user of that filled-up. In order to execute the above operation, for example, it is considered that a memory unit (IC chip) which holds information relating to the waste liquid reservation amount must be provided on the waste liquid unit and information relating to an expected waste liquid amount is written into the memory unit when an operation in which waste liquid is generated is executed.
However, if the waste liquid unit is drawn out while information is being written into the memory unit, the information cannot be written into the memory unit properly. Then, the waste liquid reservation amount in the waste liquid unit cannot be grasped properly. As a result, there arises a risk that waste liquid overflows in the apparatus.
Accordingly, considering the above situation, it is preferable that attachment and detachment of the waste liquid unit be performed requisite minimum times essentially. However, if the waste liquid unit is configured to be detachable, the waste liquid unit is exposed to an outer surface of an apparatus main body of the ink jet printer. Therefore, a user is easy to mistakenly draw out the waste liquid unit by mistake.
Further, in order to prevent the waste liquid unit from being drawn out carelessly, the following configuration can be considered to be employed, for example. That is, an openable and closable cover which opens and covers the waste liquid unit is provided and a sensor dedicated to detect opening and closing of the cover is provided. With this, at least a possibility that the waste liquid unit is drawn out is detected in advance. When the sensor detects the possibility that the waste liquid unit may be drawn out, the operation of the maintenance unit is stopped immediately.
With this configuration, at least flow-out of waste liquid in the apparatus, which is caused when the waste liquid unit is drawn out while the maintenance operation is being executed on the ink jet recording head, can be prevented from occurring. However, in this case, the apparatus is largely increased in cost, and in addition, this configuration may lead to the waste of resources and is not preferable since the waste liquid unit is rarely exchanged.